TOKYO, March 13 (Xinhua) -- Tokyo stocks were essentially flat Tuesday morning owing to investor caution about U.S. tariff hikes and Japanese politics following a renewed influence-peddling scandal involving Prime Minister Shinzo Abe.

The 225-issue Nikkei Stock Average lost 34.58 points, or 0.16 percent, from Monday to 21,789.45.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, fell 1.48 points, or 0.08 percent, at 1,739.82.

Oil and coal product, mining and iron and steel-linked issues comprised those declined the most by the morning break.